TDragImageList class
A multi-resolution list of Images used during Drag operations.
Declaration
TDragImageList = class(TCustomImageList)Inheritance
Descends from it: TImageList
Description
TDragImageList is a
TCustomImageList descendant which
provides a multi-resolution container for images displayed when a drop-drop
operation is active. A drag image is shown when a drag operation is active
and a DragImageList has been supplied.
TDragImageList overrides and reimplements methods from the ancestor to support the TDragImageListResolution type used in the image Resolution property. Additional properties and methods are provided to work with a drag image and its hot spot when the operation is started or stopped, and when the mouse position is changed.
In drag-dock operations, a drag image is not typically displayed since the DockRect frame already provides visual feedback.
This is a general overview of the usage of this class:
- SetDragImage selects an image from the list, and defines the hotspot within this image. Te hotspot typically is the offset of the mouse position to the origin of the dragged control.
- BeginDrag starts dragging, the image is shown at the starting location.
- DragMove moves the image.
- EndDrag stops dragging, the image is removed from the screen.
TDragImageList is the ancestor for the TImageList class defined in the LCL. It is also the type returned from the GetDragImages method in TControl.
See also
Properties
DragCursor | public | The cursor shape to use while dragging. |
DragHotspot | public | The position of the HotSpot image, i.e. the offset to the mouse position while dragging. |
Dragging | public | True if dragging in progress. |
DraggingResolution | public | Gets the scaled image resolution with the drag images for the list. |
Resolution | public | Gets the image resolution for the specified image width. |
Methods
GetResolutionClass | protected | Gets the class type used to create image resolutions in the list. |
Initialize | protected | initializes the cursor shape and image index for the list. |
BeginDrag | public | Start dragging an image; returns True if successful. |
DragLock | public | Show drag image during drag operation. |
DragMove | public | Shows the drag image at a new location. |
DragUnlock | public | Hide the drag image. |
EndDrag | public | Finish dragging of the image, restore the old cursor shape. |
HideDragImage | public | Hides the drag image without unlocking the window. |
SetDragImage | public | Set index of dragged image and hotspot. |
ShowDragImage | public | Displays the drag image. |
Inherited
From TCustomImageList (87)
Add AddIcon AddImages AddLazarusResource AddMasked AddMultipleResolutions AddResourceName AddSlice AddSliceCentered AddSliced AllocBy Assign AssignTo BeginUpdate BkColor BlendColor Change CheckIndex Clear ClearOverlays Count Create CreateSize DefineProperties Delete DeleteResolution Destroy DoAfterUpdateStarted DoBeforeUpdateEnded Draw DrawForPPI DrawingStyle DrawOverlay EndUpdate Equals FindResolution GetBitmap GetFullBitmap GetFullRawImage GetHotSpot GetIcon GetRawImage GetResolution Handle HasOverlays Height HeightForPPI HeightForWidth ImageType Insert InsertIcon InsertMasked MarkAsChanged Masked Move OnChange OnGetWidthForPPI Overlay Overlays ReadAdvData ReadData Reference ReferenceForPPI RegisterChanges RegisterResolutions Replace ReplaceIcon ReplaceMasked ReplaceSlice ReplaceSliceCentered ResolutionByIndex ResolutionCount ResolutionForPPI Resolutions ResolutionsDesc Scaled ScaleImage SetSize SetWidthHeight ShareImages SizeForPPI StretchDraw UnRegisterChanges Width WidthForPPI WriteAdvData WriteData
From TLCLComponent (8)
DecLCLRefCount GetWSComponentClass IncLCLRefCount LCLRefCount NewInstance RemoveAllHandlersOfObject WidgetSetClass WSRegisterClass
From TComponent (73)
_AddRef _Release BeforeDestruction CanObserve ChangeName ComObject ComponentCount ComponentIndex Components ComponentState ComponentStyle DesignInfo DestroyComponents Destroying ExecuteAction FindComponent FreeNotification FreeOnRelease GetChildOwner GetChildParent GetChildren GetDeltaStreams GetEnumerator GetIDsOfNames GetNamePath GetObservers GetOwner GetParentComponent GetTypeInfo GetTypeInfoCount HasParent iicrGetComponent InsertComponent Invoke IsImplementorOf Loaded Loading Name Notification ObserverAdded Observers OnGetDeltaStreams Owner PaletteCreated QueryInterface ReadDeltaState ReadDeltaStream ReadState ReferenceInterface RemoveComponent RemoveFreeNotification RemoveFreeNotifications SafeCallException SetAncestor SetChildOrder SetDesigning SetDesignInstance SetInline SetName SetParentComponent SetSubComponent Tag ToString TToStringNameMode UpdateAction Updated UpdateRegistry Updating ValidateContainer ValidateInsert ValidateRename VCLComObject WriteState
From TPersistent (3)
From TObject (35)
AfterConstruction CheckDisposed ClassInfo ClassName ClassNameIs ClassParent ClassType CleanupInstance DefaultHandler DefaultHandlerStr Dispatch DispatchStr Disposed DisposeOf FieldAddress Free FreeInstance GetDisposed GetHashCode GetInterface GetInterfaceByStr GetInterfaceEntry GetInterfaceEntryByStr GetInterfaceTable GetInterfaceWeak GetLastCastErrorInfo InheritsFrom InitInstance InstanceSize MethodAddress MethodName QualifiedClassName StringMessageTable SystemHasExtendedRTTI UnitName
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